It is not limited to this rule. Everything regional is at the discretion of the region - the region can make/modify classes however it wishes.
Yep. I could buy an NSX for under 30k. Keeping the thing running is another thing. Vivek's has broken at nearly evey national event it participates in.
It's all moot - this is a granular draft to suggest the direction the STAC thinks might be useful, not to hammer out details. None of these cars you mentioned will be in STR - even locally - ever.